1. Field of the Invention
The present invention relates to an apparatus for detecting the position of particulate materials on a workpiece, and more particularly to a pattern position detecting apparatus utilizing an energy beam, adapted for identifying the edge position or the width of a photoresist pattern employed in the manufacturing process of semiconductor devices.
2. Related Background Art
Semiconductor wafers employed for the manufacture of semiconductor devices such as IC's and LSI's are subjected to various treatments in the course of manufacturing process. For achieving desired performance it is important to accurately control the width or dimension of the circuit pattern or alignment mark pattern in the manufacturing process, and for this purpose there is required an apparatus for detecting the pattern with a high precision.
In the U.S. patent application Ser. No. 06/808,932 filed Dec. 13, 1985 and assigned to the assignee of the present application, is disclosed an apparatus for scanning the wafer with a probing laser beam and detecting the reflected light, scattered light and fluorescent generated when a pattern edge is scanned with said laser beam, thereby detecting the position of said edge.
In such apparatus, however, the measurement of a photoresist pattern may result in a damage (destruction or deterioration) of said photoresist as the result of exposure thereof to said laser beam for measurement. The possibility of said damage has been increased by the measures adopted for improving the precision of detection of such apparatus. More specifically, for improving the precision of detection, there have been employed to shorten the wavelength of laser beam through the use of HeCd laser or Ar laser, and to reduce the probing beam diameter by concentrating the beam with an optical system. The former method may bring the wavelength of the laser beam within the photosensitive wavelength range of the photoresist, while the latter method enhances the deterioration of photoresist due to the increased density of the laser beam irradiating the photoresist, thereby increasing the possibility of damage.